A proposed $7,500 fine against BART for its taxpayer-funded campaign supporting a $3.5 billion bond measure is a joke.

The penalty recommended by the staff of the state Fair Political Practices Commission would be merely a rounding error compared to the bounty the transit district will collect from Measure RR, the property-tax increase voters approved two years ago. For BART, the fine is simply a cost of doing business. Indeed, in local government agencies across California, use of public funds for political campaigns have become the norm.

It’s illegal. But the abuse will continue until the FPPC, district attorneys across the state, including Alameda County’s Nancy O’Malley in this case, and Attorney General Xavier Becerra start cracking down. It must be stopped. Elected officials must be held accountable.

BART’s hardly alone. For example, the East Bay Regional Park District this year launched a political campaign for its property tax extension. Los Angeles County in 2017 ran television ads appearing to back a quarter-cent sales tax increase to help the homeless. And El Cerrito officials in 2014 conducted a publicly funded campaign to double the city’s sales tax.

No matter what the causes’ merits are, public money should be used to deliver services, not campaign for tax increases. The law and the courts have been clear on that point. Local agencies may provide information about ballot measures, but they may not become advocates.

Local officials seem to think that as long as they don’t say “vote ‘yes’ ” that they haven’t crossed the legal threshold. “We were diligent to keep all material educational, never suggesting how people should vote,” BART spokeswoman Alicia Trost said after the fine was announced.

They still don’t get it. The style, tenor and timing of the communication is another critical determinative of whether it crosses a legal line. So when BART produced videos in the middle of the campaign with what the FPPC called “inflammatory and argumentative statements,” the transit agency crossed the line.

“We need to spend more dollars to get it (BART) into a more modern condition,” said a rider in one of the videos produced at public expense. “It’s time to rebuild,” BART championed in the other.

This wasn’t merely information; this was pure political advocacy, which permeated the material BART offered throughout the campaign. As we said at the time, they lied to voters about the cost of the bond measure and conducted what we called a “legally questionable taxpayer-funded campaign.” It turns out we were right. But sadly, there have been no meaningful consequences.

The fault lies partially with the FPPC, which usually issues trivial fines. The commission on Dec. 20 will consider the recommended BART penalty. But in fairness, the commission’s jurisdiction is usually limited to penalties for reporting violations — in this case, BART’s failure to disclose the political expenditures.

The much more serious transgression, the use of public money for political purposes, is usually criminal — and falls under the jurisdiction of district attorneys and the state attorney general. Until they take this seriously, the abuse will continue.